Gardening: Abs-olute exercise

If you're no gym bunny but want to be fit, try some composting, writes Meg Liptrot.

Some work with the spade will soon get you in trim form. Photo / Supplied

One of the reasons I took up gardening was to get out of the office and get some fresh air and exercise the old-school way. I'm certainly no gym bunny and I could never come to grips with the idea of paying to exercise.

Among the best calorie-burning exercises you can do in the garden are turning a large compost heap, or digging a new garden.

Lifting a fork of heavy material gives a pretty good ab, pec and bicep workout, that's for sure. For those not keen on raising a sweat, there are plenty of ways to make a compost with low physical input. My grandmother continued making compost and had a wonderful vege garden into her early 90s.

Why bother composting? Well, apart from the exercise, methane, which rotting organic waste gives off, is one of the major gases contributing to global warming. Kitchen scraps put in the rubbish bin end up in the landfill and will rot in an anaerobic, stinky way. Composting reduces landfill methane emissions.

Organic waste is also a valuable resource. Homemade compost can be cycled back into the ground for other plants and soil microbes to use, giving you abundant flowers, veges and fruit. It will help turn your soil into a nice friable loam, rich in organic matter - and make digging easier.

If you don't have room for the classic three-bin system - which is the best substitute for a gym workout - there are all sorts of composting bin types available for small properties. One of these is the inexpensive Gedye bin, shaped like a Dr Who Dalek.

These bins are suitable for properties which have only small quantities of organic waste at a time. The decomposition of plant material and kitchen scraps happens over a longer period and is called "cold" semi-aerobic composting.

These open-bottomed Gedye bins are designed to be placed on soil, so worms can come in and do their magic, breaking down the organic waste quickly and doing the digging for you. It is best to have two bins side by side, so one full bin is curing while you start filling another.

To create a faster, hot aerobic compost in a small space, insulate your bin. Fill your whole bin all at once, layering carbon and nitrogen materials (browns and greens) as you go. Layer fresh grass clippings to help generate heat. The key with a hot system is to get air moving from underneath, so put the bin on some stiff wire mesh on bricks.

The budget way to make an insulated bin is to use a double layer of old coreflute signs - that's the material used, for example, by real estate agents. Bind the signs in a square with a drop-down lid and open base. This will work a treat. Paint your bin in a dark colour to help it absorb the sun's rays. Don't aggravate the local real estate agents - ask for some old signs.

Ins and outs of composting

* Finished compost is pleasant, crumbly and shouldn't smell. It should be slightly damp (like a squeezed-out sponge).